Lily James and Cher join returning stars Amanda Seyfried, Colin Firth, Christine Baranski and (yes) Meryl Streep for another ABBA-soundtracked musical comedy, set in the present and the past.

Mamma Mia! Here We Go Again will reunite the star-studded cast — including Amanda Seyfried, Meryl Streep and Colin Firth — a decade after the initial musical romantic comedy came out.

Plans for the film were revealed in May 2017, with much of the original cast attached to the project. Over the last year, a group of newcomers, led by actress Lily James and Cher, signed on to portray characters of Kalokairi's present and past.

The film picks up with Sophie Sheridan (Seyfried), last seen as a bride-to-be, pregnant and single just as her mother, Donna (Streep), was years earlier. To comfort Sophie, Donna's friends and former bandmates, Rosie (Julie Walters) and Tanya (Christine Baranski) share stories of Donna in her adventurous youth, which unfold onscreen with the new cast playing the younger versions of the musical's established stars.

The majority of the film's soundtrack comes from the original hits of ABBA, the Swedish pop group whose music served as the basis for the first film and original Broadway musical. It was confirmed that Benny Andersson and Bjorn Ulvaeus, the composers and founding members of ABBA, have penned original songs and lyrics for the sequel and act as executive producers.

There's still time to watch (or rewatch) the original film on Netflix before Universal and Legendary release the sequel on July 20, but here's everything you need to know before stepping into the theater.

MAMMA MIA! HERE WE GO AGAIN CHEAT SHEET:

WHO

It's clear from the trailers that most of the film's original cast has returned to guide present-day Sophie, bringing together the group of acclaimed actors once again.

Returning cast:

Christine Baranski plays Tanya Chesham-Leigh, one of Donna's friends and former bandmates, now a rich three-time divorcee.

Julie Walters plays Rosie Mulligan, one of Donna's friends and former bandmates, now an unmarried, fun-loving author.

Pierce Brosnan plays Sam Carmichael, now married to Donna and Sophie's stepfather, possibly her father.

Colin Firth plays Harry Bright, also Sophie's possible father and a British banker.

Dominic Cooper plays Sky, Sophie's fiancé in the first film, although their relationship status in the second film is unclear.

As the returning characters offer Sophie comfort and advice, the pic jumps back in time to show how Donna came to live on the Greek island and meet Sophie's three possible fathers, played by the movie's newcomers.

New cast:

Lily James plays young Donna Sheridan. The actress joined the film in July 2017, as she was in theaters in Baby Driver. James previously starred in 2015's Cinderella, in which she demonstrated her singing ability by crooning "A Dream Is a Wish Your Heart Makes." Of the tracks released so far, James can be heard on "When I Kissed the Teacher" and "Waterloo," but as the frontwoman of Donna and the Dynamos, audiences can expect to hear James leading plenty of ABBA's most popular songs.

Jessica Keenan Wynn plays young Tanya. Before joining James as one of the three Dynamos, the stage actress starred as Heather Chandler in the original off-Broadway cast of Heathers: The Musical and as Cynthia Weil in Beautiful: The Carole King Musical on Broadway. Wynn prepared for the role by studying her counterpart, Baranski. "One of the best things is ABBA music transcends generations," Wynn told NBC.

Alexa Davies plays young Rosie. The Welsh actress is best known for her role on the British television sitcom Raised by Wolves. Throughout shooting, Davies posted plenty of pictures with her castmates on Instagram, thanking her fellow Dynamos for making "this experience the best it could be."

In the first 15 minutes of the pic, audiences find out that Donna died a year prior to the sequel.

Creator Judy Craymer told THR that Streep was a part of the decision to reduce Donna's role in the film.

"I think she felt that she liked the idea of leaving this to the younger ones and she wanted to be involved, but she wasn't gonna take on such a big role," Craymer said.

WHAT

The trailers emphasize that present-day Donna is not available to help her daughter as she deals with the weight of motherhood and reopening her mother's old villa, now the Hotel Bella Donna. In her mother's place, Tanya and Rosie, along with Sam, Bill and Harry, offer Sophie comfort and guidance through stories of Donna as a young woman, discovering romance and the wider world with her best friends.

Such stories, it seems, will illuminate both the paternity puzzle of the first film and reflect the paralleled experiences of Sophie and her mother as the sequel jumps back and forth in time.

Although reviews have been mixed, the film has been received positively, with a rating of 85 percent on Rotten Tomatoes as of the Thursday afternoon before its release.

THR film critic Leslie Felperin writes in her review that the sequel is "faintly disappointing" and that the follow-up to the jukebox musical "is the cinematic equivalent of a B-side: adequate, blessed with a few good hooks and likely to have its fervent fans. But no one would be paying much attention if the other one hadn’t been such a big deal."

WHERE

While the new film is again set on the fictional Greek island of Kalokairi, where Sophie maintains her mother's villa, the producers chose to move the filming location from the Greek island of Skopelos to Vis, an island off the coast of Croatia.

Universal Pictures and Legendary Entertainment will release the sequel on July 20 in the U.S., almost exactly 10 years since the release of the original film, which debuted on July 18, 2008. It will unspool in various countries overseas, including many in Europe, that same week.

Adapting ABBA's greatest hits into the plot, Mamma Mia!'s soundtrack sits as the centerpiece of the film for fans of the pop group and the original musical, which premiered on Broadway in 1999 and has been performed over 5,000 times.

The full soundtrack, released July 13, features ABBA songs like "Why Did It Have to Be Me?" and "Angel Eyes."

Three of the 18 tracks —"Waterloo," "When I Kissed the Teacher" and "Fernando" — were released as singles before the debut of the full album.

While Mamma Mia! was a success with American audiences, the $52 million film was an even bigger hit at the international box office, racking up 76 percent of its global total overseas and amassing $609.8 million overall. If the excitement surrounding the last film carries onto Mamma Mia! Here We Go Again, the filmmakers can expect to rake in more money this summer.

Baranski also told THR that she feels this year's heavy news cycle makes the time right for a joyful musical.

"We are living in very dark times, and I think to have a movie as sensuous and optimistic as this new one will make people so happy," she said. "We need Mamma Mia! 2 more than we even needed the original. The world was still sane then."